Log Sheet Replacement Etiquette

I have come across a few micro caches where the log sheet is too full or too wet to sign. It seems the thing to do is to add a log sheet. But what if the cache container is too small to accommodate both the new log sheet along with the one that is too full or too wet - what is the protocol on what to do with the old log sheet?

I have run across this three times now and in each case I got the log returned to the owner either in person or in 1 case I dropped off a missing micro in one of his other caches. I don't know about most people but I have kept most of the full logs from my caches. You would be surprised how many people find your caches and don't log them online.